Blood Crystals: What are they?

These crimson crystals have been present ever since the Burning Crusade xpac and there has been no clear explanation on what their nature is. They were commonly associated with the Blood Elves, also noticed polluting the Fallen Sky Ridge at Hellfire Peninsula. Moreover, the Draenei have spotted some of them at their starting area and they attempt to clear them.
The same crystal appeared in the revamped Blasted Lands as an actual Blood Magic artifact along with some Blood Mage NPCs. Furthermore, in MoP 5.2 Blood Elf side, we see them using those crystals to channel some crimson energies, while Lor'themar mentions that he found blood magic technology made by the Titans which is to be immediately studied.

I am surprised that no thread has been made so far to look into the subject. Do all of these clues form a picture? Let me hear your thoughts on this.

They are crystals used by blood mages. (Which alot of blood elf mages are). I could be wrong here but I think they are for storing power that the blood mages can draw from when they are out in the field. Human mages have to eat and drink to regain the power to keep casting but the blood mages can draw from the crystals to keep casting for an extended time.

Also they can be used as shield walls to defend against enemy magic. Eg. The ones at quel'danas and the new ones in 5.2.

Interestingly, they are called "Defense Crystal" -or something like that- in The Isle of Thunder. Their purpose seems to be pureley defensive, they can be assumed to be some sort of magic storage with defense capabilities.

Previous appearances have described them as blood crystals, but it has never stated if they actually work with blood. It does point out though, to be a technology developed exclusively by blood elves, and the naming might be just for flavour and paying homage to the crystal's red hue. Maybe they require some blood magic to work.

Interestingly, they are called "Defense Crystal" -or something like that- in The Isle of Thunder. Their purpose seems to be pureley defensive, they can be assumed to be some sort of magic storage with defense capabilities.

Previous appearances have described them as blood crystals, but it has never stated if they actually work with blood. It does point out though, to be a technology developed exclusively by blood elves, and the naming might be just for flavour and paying homage to the crystal's red hue. Maybe they require some blood magic to work.

I'm really interested in knowing more about these crystals.

Those "blood" crystal at Isle of Thunder just shoot down Zandalari trolls on flying mounts.